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cti-python-stix2
================

This is an `OASIS Open
Repository <https://www.oasis-open.org/resources/open-repositories/>`__.
See the `Governance <#governance>`__ section for more information.

This repository provides Python APIs for serializing and de-serializing
STIX 2 JSON content, along with higher-level APIs for common tasks,
including data markings, versioning, and for resolving STIX IDs across
multiple data sources.

For more information, see `the
documentation <https://stix2.readthedocs.io/en/latest/>`__ on
ReadTheDocs.

Installation
------------

Install with `pip <https://pip.pypa.io/en/stable/>`__:

::

    pip install stix2

Usage
-----

Creating STIX Domain Objects
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

To create a STIX object, provide keyword arguments to the type's
constructor:

.. code:: python

    from stix2 import Indicator

    indicator = Indicator(name="File hash for malware variant",
                          labels=["malicious-activity"],
                          pattern="[file:hashes.md5 = 'd41d8cd98f00b204e9800998ecf8427e']")

Certain required attributes of all objects will be set automatically if
not provided as keyword arguments:

-  If not provided, ``type`` will be set automatically to the correct
   type. You can also provide the type explicitly, but this is not
   necessary:

.. code:: python

    indicator = Indicator(type='indicator', ...)

Passing a value for ``type`` that does not match the class being
constructed will cause an error:

.. code:: python

    >>> indicator = Indicator(type='xxx', ...)
    stix2.exceptions.InvalidValueError: Invalid value for Indicator 'type': must equal 'indicator'.

-  If not provided, ``id`` will be generated randomly. If you provide an
   ``id`` argument, it must begin with the correct prefix:

.. code:: python

    >>> indicator = Indicator(id="campaign--63ce9068-b5ab-47fa-a2cf-a602ea01f21a")
    stix2.exceptions.InvalidValueError: Invalid value for Indicator 'id': must start with 'indicator--'.

-  If not provided, ``created`` and ``modified`` will be set to the
   (same) current time.

For indicators, ``labels`` and ``pattern`` are required and cannot be
set automatically. Trying to create an indicator that is missing one of
these properties will result in an error:

.. code:: python

    >>> indicator = Indicator()
    stix2.exceptions.MissingPropertiesError: No values for required properties for Indicator: (labels, pattern).

However, the required ``valid_from`` attribute on Indicators will be set
to the current time if not provided as a keyword argument.

Once created, the object acts like a frozen dictionary. Properties can
be accessed using the standard Python dictionary syntax:

.. code:: python

    >>> indicator['name']
    'File hash for malware variant'

TBD: Should we allow property access using the standard Python attribute
syntax?

.. code:: python

    >>> indicator.name
    'File hash for malware variant'

Attempting to modify any attributes will raise an error:

.. code:: python

    >>> indicator['name'] = "This is a revised name"
    TypeError: 'Indicator' object does not support item assignment
    >>> indicator.name = "This is a revised name"
    stix2.exceptions.ImmutableError: Cannot modify properties after creation.

To update the properties of an object, see `Versioning <#versioning>`__
below.

Creating a Malware object follows the same pattern:

.. code:: python

    from stix2 import Malware

    malware = Malware(name="Poison Ivy",
                      labels=['remote-access-trojan'])

As with indicators, the ``type``, ``id``, ``created``, and ``modified``
properties will be set automatically if not provided. For Malware
objects, the ``labels`` and ``name`` properties must be provided.

Creating Relationships
~~~~~~~~~~~~~~~~~~~~~~

STIX 2 Relationships are separate objects, not properties of the object
on either side of the relationship. They are constructed similarly to
other STIX objects. The ``type``, ``id``, ``created``, and ``modified``
properties are added automatically if not provided. Callers must provide
the ``relationship_type``, ``source_ref``, and ``target_ref``
properties.

.. code:: python

    from stix2 import Relationship

    relationship = Relationship(relationship_type='indicates',
                                source_ref=indicator.id,
                                target_ref=malware.id)

The ``source_ref`` and ``target_ref`` properties can be either the ID's
of other STIX objects, or the STIX objects themselves. For readability,
Relationship objects can also be constructed with the ``source_ref``,
``relationship_type``, and ``target_ref`` as positional (non-keyword)
arguments:

.. code:: python

    relationship = Relationship(indicator, 'indicates', malware)

Creating Bundles
~~~~~~~~~~~~~~~~

STIX Bundles can be created by passing objects as arguments to the
Bundle constructor. All required properties (``type``, ``id``, and
``spec_version``) will be set automatically if not provided, or can be
provided as keyword arguments:

.. code:: python

    from stix2 import bundle

    bundle = Bundle(indicator, malware, relationship)

Serializing STIX objects
~~~~~~~~~~~~~~~~~~~~~~~~

The string representation of all STIX classes is a valid STIX JSON
object.

.. code:: python

    indicator = Indicator(...)

    print(str(indicator))

Versioning
~~~~~~~~~~

TBD

Governance
----------

This GitHub public repository (
**https://github.com/oasis-open/cti-python-stix2** ) was
`proposed <https://lists.oasis-open.org/archives/cti/201702/msg00008.html>`__
and
`approved <https://www.oasis-open.org/committees/download.php/60009/>`__
[`bis <https://issues.oasis-open.org/browse/TCADMIN-2549>`__] by the
`OASIS Cyber Threat Intelligence (CTI)
TC <https://www.oasis-open.org/committees/cti/>`__ as an `OASIS Open
Repository <https://www.oasis-open.org/resources/open-repositories/>`__
to support development of open source resources related to Technical
Committee work.

While this Open Repository remains associated with the sponsor TC, its
development priorities, leadership, intellectual property terms,
participation rules, and other matters of governance are `separate and
distinct <https://github.com/oasis-open/cti-python-stix2/blob/master/CONTRIBUTING.md#governance-distinct-from-oasis-tc-process>`__
from the OASIS TC Process and related policies.

All contributions made to this Open Repository are subject to open
source license terms expressed in the `BSD-3-Clause
License <https://www.oasis-open.org/sites/www.oasis-open.org/files/BSD-3-Clause.txt>`__.
That license was selected as the declared `"Applicable
License" <https://www.oasis-open.org/resources/open-repositories/licenses>`__
when the Open Repository was created.

As documented in `"Public Participation
Invited <https://github.com/oasis-open/cti-python-stix2/blob/master/CONTRIBUTING.md#public-participation-invited>`__",
contributions to this OASIS Open Repository are invited from all
parties, whether affiliated with OASIS or not. Participants must have a
GitHub account, but no fees or OASIS membership obligations are
required. Participation is expected to be consistent with the `OASIS
Open Repository Guidelines and
Procedures <https://www.oasis-open.org/policies-guidelines/open-repositories>`__,
the open source
`LICENSE <https://github.com/oasis-open/cti-python-stix2/blob/master/LICENSE>`__
designated for this particular repository, and the requirement for an
`Individual Contributor License
Agreement <https://www.oasis-open.org/resources/open-repositories/cla/individual-cla>`__
that governs intellectual property.

Maintainers
~~~~~~~~~~~

Open Repository
`Maintainers <https://www.oasis-open.org/resources/open-repositories/maintainers-guide>`__
are responsible for oversight of this project's community development
activities, including evaluation of GitHub `pull
requests <https://github.com/oasis-open/cti-python-stix2/blob/master/CONTRIBUTING.md#fork-and-pull-collaboration-model>`__
and
`preserving <https://www.oasis-open.org/policies-guidelines/open-repositories#repositoryManagement>`__
open source principles of openness and fairness. Maintainers are
recognized and trusted experts who serve to implement community goals
and consensus design preferences.

Initially, the associated TC members have designated one or more persons
to serve as Maintainer(s); subsequently, participating community members
may select additional or substitute Maintainers, per `consensus
agreements <https://www.oasis-open.org/resources/open-repositories/maintainers-guide#additionalMaintainers>`__.

.. _currentMaintainers:

**Current Maintainers of this Open Repository**

-  `Greg Back <mailto:gback@mitre.org>`__; GitHub ID:
   https://github.com/gtback/; WWW: `MITRE
   Corporation <http://www.mitre.org/>`__
-  `Chris Lenk <mailto:clenk@mitre.org>`__; GitHub ID:
   https://github.com/clenk/; WWW: `MITRE
   Corporation <http://www.mitre.org/>`__

About OASIS Open Repositories
-----------------------------

-  `Open Repositories: Overview and
   Resources <https://www.oasis-open.org/resources/open-repositories/>`__
-  `Frequently Asked
   Questions <https://www.oasis-open.org/resources/open-repositories/faq>`__
-  `Open Source
   Licenses <https://www.oasis-open.org/resources/open-repositories/licenses>`__
-  `Contributor License Agreements
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-  `Maintainers' Guidelines and
   Agreement <https://www.oasis-open.org/resources/open-repositories/maintainers-guide>`__

Feedback
--------

Questions or comments about this Open Repository's activities should be
composed as GitHub issues or comments. If use of an issue/comment is not
possible or appropriate, questions may be directed by email to the
Maintainer(s) `listed above <#currentmaintainers>`__. Please send
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